The epidemiological characteristics of severe postpartum depression requiring hospitalization have not been described. Based on the limited data available, hospitalized postpartum depression comprises approximately 5 percent of all cases and appears to disproportionately afflict socioeconomically disadvantaged women at the extremes of the maternal age distribution. However, a current and reliable estimate of the frequency of severe postpartum depression and its pattern of occurrence in relation to social, demographic, behavioral, and infant health characteristics is not available. We propose to conduct a highly efficient, yet comprehensive and population-based assessment of hospitalized postpartum depression in the large and diverse population of the State of New York by linking publicly available data resources. Using hospital discharge data, we will follow each woman forward in time for one year following births that occur in the state from 1995 through 2004. By linking delivery and depression hospital discharge records, we can estimate the prevalence and incidence of severe postpartum depression with a high degree of comprehensiveness and accuracy. We will link these data to the 2000 Census to evaluate neighborhood socioeconomic and urbanization factors, and infant hospitalization and death records. With this unique data resource, we will (1) Describe the epidemiology of hospitalized postpartum depression by identifying patterns in relation to maternal sociodemographic characteristics and geographic location;(2) Examine the relation between infant health and hospitalization for postpartum depression;and (3) Examine the relation between common complications of pregnancy, including gestational diabetes mellitus, preeclampsia, and cesarean delivery, and hospitalization for postpartum depression. This research will provide a needed basis on which to focus future etiologic and intervention research by identifying the predictors and defining the characteristics of those at highest risk for severe postpartum depression. PUBLIC HEALTH RELEVANCE: Postpartum depression requiring hospitalization is a potentially catastrophic consequence of pregnancy that adversely affects both the mother and the child and frequently necessitates the intervention of social services to provide care for the infant. Moreover, the interruption of mother-child bonding during this critical period may result in long term consequences for the child's cognitive and emotional well- being, which in itself carries a significant social cost. By clearly identifying the epidemiologic patterns of occurrence, this study will provide needed guidance regarding the design and conduct of detailed etiologic studies of the social, behavioral, and biomedical causes of severe postpartum depression.